The invention relates to fuel injection nozzles, and in particular to a fuel injection nozzle for internal combustion engines which exhibit two stages of injection. Such nozzles typically have: a valve needle, which controls a fuel exit area that has two successive, separated, at least single injection openings, and has a closing cone portion; a nozzle body defining a valve seat, with the closing core portion cooperating with the valve seat to control the area that was opened earlier; and a control member that serves to control the area subsequently opened, with the control member being arranged so as to be relatively axially movable in a blind bore of the valve needle that is open toward a corresponding injection opening.
In a known fuel injection nozzle of this type the control member is lifted as a drag link away from its associated valve seat after a certain needle stroke and thereby frees a second fuel exit area. The carrier device of the drag link, however, is expensive for reasons of efficiency in production and also wears out, so that the opening control point of the second injection area gradually is pushed back over time, which is disadvantageous for the noise production of the engine. This is especially disadvantageous in diesel engines, which operate without a precombustion chamber. In these direct-injection engines, in addition to the exact point in time of the opening of the second injection area, the manner of opening also plays a role. Thus it is somewhat desirable, that the second fuel exit area is opened gradually, for example between idling and low partial load, toward full load. The disadvantages of an unsatisfactory control is the relatively great roughness in the transitional rpm range, as well as a worsening of the fuel consumption, the exhaust and the performance.